Cooler for viscous liquids



Sept. 2l, 1948. 'Y s. K. ANDERSEN y 2,449,922

COOLER Fon VIscoUs LIQUIDs Filed March 1o, 1945 5 sheets-sheet 1 4Q?....5'7. :.S-50 65 65% 15 lif,

Ctkorneg sept. 21, 194s.

s. K. ANDERsEN COOLER FOR VISCOUS LIQUIDS L 5 Sheets-Sheet 2 Filed March10, 1945 Sept 21 1948- s.-K. ANDERSEN 2,449,922

COOLER FOR VISCOUS LIQUIDS Filed Match 1o. 1945 l s sheets-sheet sGttorncg.

s. K. ANDI-:Rsx-:N 2,449,922

COOLER FOR YISCOUS LIQUIDS sept. 21., 194s.

5 Sheets-Sheet 4 Filed March l0, 1945 l Y nventor:

5095A' A24/M5255,

Sept. Z1, 1948.

Filed March-10,1945

s. K. ANpERsl-:N 2,449,922

c oomzn Fon vrscous LIQuIns 5 sheets-sneu 5 INVENTOR. SOREN K. ANDERSEN,ATTORNEY Patented Sept.-21,` 19418 UNITED y STATES APATENT OFFICECOOLEEFORtIsgUS LIQUIDS Y Soren K. Andersen, Los Angeles, Calif.,assigner to The Garrett Corporation, Airesearch Mannfaeturing Companydivision, Los Angeles, Calif., a corporation of California ApplicationMarch 10, 1945, Serial No# 582,080

12 Claims. (Cl. 257-128) This invention relates to coolers for liquidswhich are viscous when cold, and is particularly useful in oil coolersfor aircraft engines.

Such oil coolers have as' their primary function to regulate thetemperature, and thus the viscosity, of the'lubricating oil of anaircraft engine, and are required to perform this function under widelyvaryingconditions of operation. At times they are burdened with a heavycooling load, for example-When the temperature of the ambient air ishigh, and for this purpose the cooler must have a high heat exch-angecapacity. Consequently, it is customary to provide the cooler with alarge number of tubes for the flow of a coolant, which tubes are spacedrelatively closely together to provide restricted passages for the mosteicient exchange of heat between the oil owing through such passages andthe coolant iiowing through the tubes.

At other times the coolers may be required to operate in ambient airhaving a temperature far below zero, and in many cases the descent tosuch subzero temperatures may be quite abrupt, and under such conditionsthe mechanism which is lusually provided for regulating the quantity ofcoolant flowing through the tubes, may not act `quickly enough toprevent a rapid chilling of the tubes suillcient to cause the layer's ofoil adjacent the outer surfaces of the tubes to congeal thereagainst orto become so viscous as to adhere substantially immovably to such tubesurfaces. In other cases, the aircraft may be forced to stand in subzeroweather for sumcient length of time to permit the oil within the coolercore to thicken.

` Under such conditions, the resistance of the relatively restrictedpassages between the heat exchange tubes to the flow of the thickenedoil therethrough, may become so great as to virtually prevent anysubstantial ow through said passages, even under the high pressuresdeveloped by the pumping apparatus of the oil circulating system. `Therestriction of the passages between the tubes by the congealment oflayers of oil against the outer surfaces of the tubes, heightens thisincreased core resistance.

It is customary to employ, in suchcoolers, a`

warm up chamber in the nature of a bypass between the inlet and outletof the cooler, which may be subjected, through suitable yielding valvemeans, to sufcient resistance to the flow of the oil therethrough to`normally urge the flow through the cooler core, but operative to bypassthe oil or a substantial portion thereof when the core resistancebecomes abnormally high as aforesaid. The oil thus bypassed is notsubjected.

to any substantial cooling eiect `and consequently may acquire andmaintain a sufliciently high temi l perature to impart heat to thecooler for the purpose oi thawing or reducing thel viscosity ofthethickened oil therein. The use of such warm up Abypassing means has beenquite common for a number of years, but even though supplied with suchwarming up means, coolers have often failed under severe operationconditions.- In many cases. such coolers would, undersevere lowtemperature operating conditions, display a progressive waxing of thetubes beginning in the center of the cooler and spreading outwardly,accompanied by .a progressive localization of mareas- Having in mind theforegoing problems, the.

general object of the present invention is to provide a cooler forliquids that are viscous when cold whichis adapted to provide a maximumof forced distribution of the liquid into the core under congealmentconditions wherein the layers of liquid adjacent the tube surfacesbecome so viscous as to adhere substantially immovably to 4the tubesurfaces or to form waxed illm thereon.

More specifically, it is an object of the invention to provide an oilcooler having coolant tubes which are spaced sumciently closely toprovide adequate cooling efliciency under heavy cooling loads, andyetwhich is adapted to maintain a path or paths of "free flow" throughthe cooler core from the inlet to the outlet in which the liquidisepermitted not only to now. adjacent the Jacketed walls which arewarmed by the circulation of a heated fluid through a warm up chamber,but are also permitted and urged under pressure to penetrate the core soas to promote anticongealing and de-congealing ilow into the heart ofthe core where the waxing has been previously most pronounced.

It is a further object to provide a cooler of the gassoso v' core(preferably along the bellies which divide the core into ow chambers),all of said ow passages being of less iiow resistance than the passagesbetween the majority oi the tubes and being unrestricted throughouttheir length and so connected to each other as to collectively dene afree now" channel which not only extends substantially uninterruptedlyfrom the inlet to the outlet of the cooler, but also penetrates into thecore and is adapted to direct and urge the flow of warmed oilinto thecore. I

A further object of the invention is to provide a. coolerof thecharacter set forth herein having one or more bailies with portsadjacent the ends thereof, and with supplementary ports spaced from thefirst named ports toward the center of the cooler and adapted to providefor a limited bleeding of liquid from one flow chamber to another, suchas to facilitate the "free ow" circulation under congealment conditions.

A further object of the invention is to provide a cooler having a corewhich is composed of a plurality of bundles of tubes separated bybaffles,

.a portion ofthe tubes at the periphery of the quick thaw-out means, medAugust 25, 1942, and

Serial No. 470,156, for Oil cooler, filed December 26, 1942.

Further objects and advantages of the inven-` tion will be brought outin the following parts of the speciilcation.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is a sectional View of the cooler taken on the verticallongitudinal median plane of the cooler;

Fig. 2 is a cross sectional view taken as indicated by the line 2-2 ofFig. 1;

Fig. 3 is a perspective view looking toward the bottom ofthe inlet andoutlet tting of the cooler.

Fig. 4 is a perspective view, to reduced scale, of the cooler-muil;

Fig. 5 is a perspective view of one of the baille plates of the cooler;

Fig. 6 is a perspective view of a pinched halftube employed in thecooler;

- Y 4 to side of the shell III, and have a length nearly as great asthat of the shell III.

Referring to Fig. 5, each baiiie plate I4 has near one end port meansconsisting of aligned openings I5 and I6. The openings I6 are closetothe side edges, and preferably are open to the side edges I1, for apurpose which will be hereinafter described. Between the ports I5 and IBand the center of the plate there are supplementary open'- ings I8. Thebaille plate I4 is of wave form, at least the ends I9 and 20 thereof, tocooperate with hexagonal tube ends, as shown in Fig. 2.

Fig. 7 is an enlarged fragmentary section taken as indicated by the line1-1 of Fig. 6;

Fig. 8 is a view of one side of a cooler embodying the invention withportions of the warm up jacket and shell wall broken away to illustratea core periphery composed of tubes of normal proportioning the shelldimensions; and

Fig, 9 is a detailed sectional view of the same taken as indicated bythe line 8-8 of Fig. 8.

As best shown in Figs. 1 and 2. the oil cooler comprises a drum or shellIII of tubular form, that is to say,'this shell is open at both ends soas to have the characteristics of a tube. The shell I0 is preferablycylindric, andY around the exterior there is a. muff II defining a warmup chamber I2. 'I'he interior of the shell is divided into a series offlow chambers I3 by bame plates I4 which are of rectangular outline, andextend from side Along the Yside of the baiile plate, between the endsI9 and 20, there are flanges 2I for engagement with the inner face ofthe shell I0, also as shown in Fig. 2.

The muli II, as shown in Fig. 4, comprises a wall 22 curved to nearcylindric form so that there will be a space 23 between the ends 24 ofthe wall 22. Flanges 25 are bent inw'ard from the curved edges of thewall 22, the inner edges 28 of these anges 25 engaging the external faceof the shell IU, and being joined therewith, as by soldering, so Ias toform the end closures for the warm-up chamber I2 of the cooler.

The muif II is mounted on the shell I0 so that the gap 23 between theends 24 thereof will be disposed at the top of the cooler, and in thisspace there is a fitting 21 having the general form of an invertedrectangular pan. This fitting, as shown in Fig. 3, has a top wall 28,end walls 29, and side walls 30 and 3|, deiining within the fitting 21 aspace which is divided by transverse walls 32 and 32 into an inletchamber 33, bypass chamber 34, and outlet chamber 35, with cooperatinginlet port 36, bypass port 31, and outlet port 38, all of which arepreferably formed in the top wall 28 of the fitting 21. Along each sideWall 33 and 3I of the iitting 21, there is an outstanding lip 38, theupper portion of which lip extends parallel to the upper face of theshell III, and the end portions 4I of the lip curve down ward'to meetthe face of the shell III. These lips 319 project under the ends 24 ofthe wall 22 from which the muff Il is formed, and the end portions 4I ofthe lips lie within the ends of the flanges 25 of the drum and muff II.The ends 24 of the mui II and the lip 39 of the fitting, lying thus inoverlapping relation, are soldered together sorthat strong joints aremade therebetween. The lower faces of the walls 23, 3B, 3|, 32, and 32',which engage the upper surface of the shell Ill, are soldered totheshell so that the fitting 21 is rigidly secured in place.

Referring again to Fig. 3, it will be noted that the forward interiorportion of the side wall 3l is cutaway, below the lip 39, to provide aport 42 for connecting the inlet chamber 33 of the fitting 31 with oneendof the warm up chamber up chamber I2 with the bypass chamber 34 ofthe fitting 21.

As shown in Fig. 1, the barile plates I4 are alternated with respect tothe ports thereof so that the ports I5 and I6 of consecutive baiileplates will be disposed at opposite ends of the cooler. These ports I5and I6 and likewise the supplementary ports I8 connect the sections I3in series so that a zig-zag path for the iiow of gether so as to havethe appearance'of a honeycomb, and which are secured together and toadjacent wallmembers of the cooler so as to close the ends of thesections I3, such securing o1 the' hexagonal end portions 46 of thetubes being ordinarily accomplished by soldering.

The diametral dimensions of the enlargements 46 on the ends of the tubes41 determine the spacing of the tubes, or, in other words, determine arelationship between the tubes which shall be referred to hereinafter asthe normal spacing of the tubes. 'I 'his normal spacing of the tubes isdesigned so as to provide relatively small interstices between theexteriors of l.adjacent tubes. through which the oil undergoing cooling.action may flow in a manner to accomplish an efficient transfer of heatfrom the oil to the metal walls of the tubes 41. of. tubes 46 is sodimensionally formed with relation to the lateral dimensions of thechamber I3 in which it is contained as to provide between the sides ofeach..v bundle and the wall of the shell I6 a definite oil flow passage60, and each bundle 46, lying above a baille plate I4, is so formed withrespect to the vertical dimension of the section I3 in which'it iscontained that a denite flow passage 6I is provided between such bundleand the upper face of the baille plate I4 therebelow. The flowy passages60 result from the placement of circular spacer strips 69 within theends of the shell I II. 'I'he flow passages 6I result from the placementof lateral spacer strips 66 between the end portions of the baitleplates I4 and the row 6I of tubes 41 immediately thereabove. This lowerrow or bank 6I of tubes in each section abovev the lowermost section isspaced at a distance from the row of tubes 62 thereabove, greater thannormal, this being accomplished by placing between the ends 48 of thetubes in the rst row 6I and the ends 48 of the tubes in the second row62 lateral spacer strips 66. In this way lateral flow passages 64 areformed between the first and second rows of tubes 6I and 62.

In Figs. 1 to 'I inclusive, the diameters of the tubes 41 and thehexagonal heads thereof are exaggerated with reference to the diameterof the cooler shell in order to simplify the drawings. In Figs. 8 and 9respectively I have shown the result in a cooler core in which the tubedi` mensions are shown in substantially accurate conformity ltoconventional proportloning between tubes and shell of known coolers.Refer- 'ence is of course made here to the relationship between thenormal spacing between tubes on the one hand and tube diameter and shelldiameter on the other hand. It will be noted that' the spacer rings 59provide, in conjunction with the tubes and half-tubes. a peripheralor'header flow space which is well defined, which is not obstructed atany point, which receives heat throughout its length from the `warin upchamber` I2, and which. as a result of the foregoing characteristics,provides a relatively low resistance flow passage for the distributionof warmed oil to the low resistance ow passages 6I pene- Each bundletrating the core and also (through the apertures I1I) to the inter-tubespaces immediately adiacent the core periphery, as describedhereinabove.- At the same time, because of the unobstructedcharacteristics of the flow passage and its connection to the lowresistance ilow passages 6I, penetrating the cooler, excessive bypassingthrough the flow passage 66 is inhibited and sumcent resistance isdeveloped therein to promote the penetration of the warmed oil to thecore through the low resistance flow passages 6I and the apertures 1I.

In Figs. 6 and 7 I have shown the characteristics of the pinchedhalf-tube 66 which is employed around the periphery of the core of thecooler in spaces where a regular, full sized, tube will not llt. Thishalf-tube 66 has a cross sec- 'tion corresponding to half of a hexagonof the size of the normal tube ends or enlargements4 46. Itl has threewalls 66, 61, and 66 of the same width, the walls 66 and 66 beingdisposed at angles a of 120 relative to the wall 61. A wall 69 connectsthe remaining edges of the walls 66 and 66 and is substantially twicethe width of the wall 61. When two of the tubes are placed together withthe walls 66 .thereof in abutment, the walls 66, 61, and 66 of the twotubes will define a hexagon, and the walls 66 of these tubes will delinea diametral plane extending between two opposite ridges or points ofthehexagon.v Each of the tubes 66 has near its ends pinched sections 16wherein the walls 66 andl 66 are moved toward each other and are broughtinto substanthe tubes 66 depressions or shallow notches which,

when the tube member 65 is assembled in a cooler core, will provideapertures1I for the flow of oil from the peripheral flow passage 60 intothe interior of the core. Accordingly, the provision of thesedepressionsl 1I' in the half-tubes 65 contribute in the coolerconstruction to the effect of obtaining -a rapid recovery of the cooler.from a congealed or partially congealed condition.

The formation of the pinched sections is accomplished by depressing aportion 12 of the wall 69, forcing a portion 13 of the wall 61 oppositethe wall portion 'l2 inward, and then squeezing the walls 66 and 66toward each other so that the moved walls in the pinched sections definesubstantially a letter N, as shown in Fig. 7.

Since the passages 56 and 6I. are each defined on oneside by a wallwhich is not cooled by air flowing thereover, there can underpractically no conditions be any waxing of theioil in contact with theuncooled wall, and there will be con- Aflow channel of lower, resistanceunder congealment conditions than the resistance of they passagesbetween the tubes.

The flow through this branching system of free flow passages may thus bevisualized by considering Figs. 1 and 2 simultaneously. From the coreinlet 44, the oil will flow in a direction generally parallel to thelongitudinal axis of the core, as indicated by the arrows 14. At thesame time, the oli will spread circumferentially in the peripheral freeilow passage 66 from the inlet 44 equally on either side of the bundleof tubes in the lowermost iiow chamber I3. This combined axial andcircumferential movement (along roughly helical ow paths) will bring theoil to the ports I at the two side extremities of the bailles I4dlviding the lowermost flow chamber I3 4from the succeeding iiow chamberI3. Then the free ow" in the passages 50 will move in a generally axialdirection, opposite to that which occurs in the lowermost chamber I3,with sumcient circumferential movement to bring the free ilow" stream upto the next baille I4 in the side port (communicating with the shellwall) therein. The iiow will alternate in this manner back and forthfrom end to end of the cooler on either side thereof until the twostreams reach the uppermost ow chamber I3 in which they will converge byhelical ilow along the shell wall to the outlet 45.

The flow `lust described is the flow which occurs in what is hereinreferred to as the "free flow" channel from the inlet to the outlet.From this peripheral channel of flow, the warmed oil will be urged topenetrate the core in the core penetrating free flow passages 5I and 64respectively adjacent the bafiles and between the rows of tubes. Thesebranching flows of-oil will also move in a direction generally parallelto the longitudinal axis of the cooler, and from such branching flows.the oil will gradually penetrate the more restricted passages betweenthe tubes so as to thaw out the congealed body of oil in the core.

Indicative of a practice now being followed with oil coolers. I haveshown a valve fitting or device 52 connected to the fitting 21 so as tocommunicate with the ports 31 and 38. This valve device 52 has a bypassvalve 53 to restrain flow of oil lthrough the bypass chamber 34 duringnormal operation of the cooler. During such normal operation of thecooler, the hot oil flows through the inlet port 35 into the inletchamber 33, as indicated by thel arrow 54 in Fig. 1. This oil then flowslaterally through the port 42 in the side wall 3| of the fitting 21, asindicated by the arrows 55 in Figs. 1 and 3, into one end of the warm upchamber I2. The oil then ilows downward through the warmup chamber tothe bottom of the cooler and enters the lowermost chamber I3 of thecooler core through the ports 44 in the bottom wall of the 'shell I0, asindicated by arrows 56. As indicated by full-line arrows 51, the oilflows serially through the consecutive flow chamber I3 to the outletport 45 and thence on out through the valve device 52.

When oil becomes thickened or congealed in the flow chambers I3 of thecooler core, the bypass valve 53 may open under pressure of the oilwhich has built up in the warm up chamber I2, and there will then be aflow of oil through the full length of the warm-up chamber I2 from theinlet chamber 33 of the fitting 2l to and through the bypass chamber 34.This partial or complete freezing up of the cooler core vmay result fromthe oil in the entire oil circulating system becoming cold-as, forexample, when the engine has been shut down for a period of time, yor asudden drop in the temperature of the air passing through the tubes 4lmay cause a partialor complete congealment of oil within the coolercore.v

When the bypass opens, the flow of heated oil through the warm upchamber I2 heats the shell I0 which then conducts heat to the oil in theclearly defined ow passages 50 lying adjacent result of the free flow inthe low resistance channels along the periphery of the core from theinlet lto the outlet. and the branching ilow from these channelspenetrating the core, is to thaw out the entire interiore! the coolerwithin a remarkably short period of time as compared to the timerequired to thaw out prior coolers of comparable eiiiciency.

While the warm up chamber has been disclosed as completely encirclingthe core, it is to be understood that the branching system of free ilo`wpassages ean be employed in a cooler wherein the warm up chamber coversonly a portion of the area of the shell.

I claim as my invention:

l. A cooler for liquids which are viscous when cold. comprising: atubular shell, a warm up Jacketsurrounding said shell to impart heat tothe outerl surface of said shell. a plurality of baille plates dividingthe space within the shell into a series of oil flow path sectionsextending from side to side of the shell, liquid inlet means for thefirst section of said series, liquid outlet means for the last sectionof said series, alternate baille plates being provided with ports atopposite ends of said sections with at least one of said ports in eachbaille plate having its periphery partially defined by said shell toprovide a zigzag path of flow serially through all of said sections inuninterrupted contact with the inner surface of said shell, a bundle ofparallel open ended tubes within each of said sections and arranged inrows generally parallel to said baille plates, the majority of the tubesof each bundle being relatively closely spaced for eiiicient heatexchange betweenv liquid flowing between said tubes and cooling fluidpassing through said tubes, means for spacing each end tube of each rowfrom said shell to provide a free flow passage for viscous liquidadjacent the inner surface of said shell, means for spacing at least onerow of tubes adjacent each baille plate from the adjacent baille plate.to provide a free` flow passage ,adjacent each baille platecommunicating with the aforementioned free flow passage adjacent theinnerv surface of said shell.

2. A cooler for liquids that are viscous when cold, comprising: a shell;means cooperating with the outer surface of said shell to denne a warmup chamber from which heat may be imparted to the shell; baille meansdividing the space within said shell into a series of iiow chambers eachhaving at least one extremity in contact with the inner surface of saidshell in an area covered by said warm up chamber; liquid inlet andoutlet means communicating with said chambers, said baille means andshell cooperating to define port means through which the liquid may ilowfrom one of said ilow chambers to another in uninterrupted contact withthe inner surface of the shell; a bundle of parallel open ended tubeswithin each of said chambers. arranged in rows generally parallel tosaid baie plate, the majority of said tubes of each bundle beingrelatively closely spaced for efilcient heat exchange between liquidiiowing between saidtubes and cooling fiuid passing through said tubes;means for spacing each baille plate from an adjacent row of tubes asuilicient distance to provide a passage of less resistance to iiow ofthe liquid under congealment conditions in which the liquid tends tocongeal upon the tube surfaces, than the resistance of the passagesbetween the tubes; and means for spacing tubes adjacent said shell adistance from said shell suillcient to' provide passages adjacenttheinner surface of the shell, of less resistance than the passagesbetween the tubes, connecting the inlet means and outlet meansrespectively to said passages adjacent the baille plates.

3. A cooler for liquids that are viscous Awhen cold, comprising: ashell; means cooperating with the outer surface of said shell to definea warm -up chamber from which heat may be imparted to the shell; baillemeans dividing the space within the shell into a series of ,flowchambers, each having at least one extremity in contact with a heatedarea of the inner surface of the shell; liquid inlet and outlet meansconnected to respective chambers, said baille means being provided withport means connecting said chambers in series between said-inlet andoutlet means to define a tortuous ow path through the cooler; a corecomprising a bundle of parallel open ended tubes within each of saidchambers, arranged in rows generally parallel to said baille means, themajority of said tubes of each bundle being relatively closely spaced,tov provide relatively restricted passages for eilicient heat exchangebetween liquid flowing in said passages and coolant passing through saidtubes; means defining between eaeh baille plate and an adjacent row oftubes, a continuous core penetrating free flow passage of lessresistance than said restricted passages under congealment conditions inwhich -the liquid tends to congeal upon the tubes; and means definingbetween the aforesaid heated areas of said shell and the adjacent tubes,peripheral free flow passages of less resistance to flow than saidrestricted passages connecting the said core penetrating free flowpassages to said inlet and outlet means respectively.

4. A cooler for liquids that are viscous when cold, comprising; a shell;means cooperating with the outer surface of said shell to define a warmup chamber from which heat may be imparted to the shell; baille meansdividing the space within the shell into a series of flow chambers, eachhaving at least one extremity in contact with a' heated area of theinner surface of the shell; liquid inlet meansand outlet means connectedto respective chambers, said baille means being provided with port meansconnecting said chambers in series with said inlet and outlet means todefacilitating the thawing of the core when it is l cold, comprising: ashell; means cooperating with the outer surface of said shell to denne awarm up chamber from which heat may be imparted to the shell; baillemeans dividing the space within the shell `into a series of flowchambers, each having at least one extremity in communication with theinner surface of the shell; liquid inlet and outlet means connected torespective chambers, said baille means being provided with port meansconnecting said chambers in series to provide a continuous tortuous flowpath between said inlet and outlet means; a core comprlslngy a bundle ofparallel open ended tubes within each of said chambers arranged-in rowsgenerally parallel to said baille plates, the majority ofthe tubes ofeach bundle being relatively closely spaced to provide relativelyrestricted passages for efllcient heat exchange between liquid flowingin said passages and coolant passing through said tubes; means providinginv each of said chambers a core penetrating free flow passage betweenadjacent rows of tubes of greater spacing and less flow resistance thanthe aforesaid relatively close spacing of the majority of the tubes tofacilitate penetration of the liquid into said bundles when the liquidis viscous; and means for spacing tubes from the inner surface of theshell to provide peripheral free flow passages adjacent said areas, ofless resistance to flow of the liquid under congealment conditions inwhich the liquid adheres to the tubes, than the resistance of the spacesbetween said majority of tubes, said peripheral free ilowpassagesconnecting said inlet and outlet means with said core penetrating freeflow passages.

6. A cooler for liquids that are viscous whenV cold, comprising: ashell;means cooperating with the outer surface of said shell to define a warmup chamber from which heat may be imparted to the shell; baille meansdividing thev space within the shell into a series of'liquid flowchamflne a tor-tuous flow path; a core comprising a Y bundle of parallelo pen ended tubes within each of said chambers, arranged in rowsgenerally parallel to said baille plates, the majority of said tubes ofeach bundle'v being relatively closely spaced to define relativelyrestricted passages for eicient -heat exchange between liquid owingbetween said tubes and coolant passing through said tubes; meansdefining between said heated areas 'of the shell andthe tubes adjacentsaid areas, a series of free' flow passages which are connected to saidinlet and outlet means and through said portf means to provide asubstantially continuous peripheral free flow channel which is of lessresistance to the ilow of the liquid under congealment conditions inwhich the liquid adheres to the tubes, than the resistance of saidrestricted passages; and means defining between said baille means and anadjacent ro'w of tubes a free fiow passage of less resistance to theflow of said liquid under said congealment conditions than theresistance of said restricted passages, said last mentioned freey l flowpassage being in communication with said bers, each having at least oneextremity in c'ontact with a heated area of the inner surface of theshell; liquid inlet and outlet means connected to respective chambers,said baille means being provided with port means connecting said cham,bers in series between said inlet and outlet means; a core comprising abundle of parallel open ended tubes within each of said chambers,arranged in rows generally parallel to said baflie means, the majorityof said tubes of eachv bundle being relatively closely spaced to providerelatively restricted passages for the efficient heat exi change betweenliquid ilowing in said passages and coolant passing through saidtubes;spacing strips interposed between said baille means and the ends of anadjacent row of tubes to provide vcore penetrating free flow passages ofless resistance than said restricted passages, to the flow of liquidunder congealment conditions vin which the liquid adheres to the tubes;and spacer rings interposed between the ends of said tubes and the shellto define peripheral free flow passages between said heated areas of theinner surface of said shell and adjacent tubes, said peripheral freeflow passages connecting said inlet and outlet means respectively tosaid' core penetrating free flow passages to provide a branching systemof free fiow passages for conveying warmed liquid into the core, andsaid peripheral free flow passages being serially connected by said portmeans to provide in said system a substantially continuous free nowchannel extending from said inlet to said outlet means.

7. A cooler for liquids that are viscous when cold, comprising: a shell;means cooperating with the outer surface of said shell to define a warmup chamber from which heat may be imparted to the shell; baille meansdividing the space within the shell into aseries of liquid flowchambers, each having at least one extremity in contact with a heatedarea of the inner surface of the shell; liquid inlet and outlet meansconnected to respective chambers, said baille means and shellcooperating to define port means serially connecting said chambers; abundle of parallel open ended tubes in each of said chambers arranged inrows generally parallel to said baille means, the majority of said tubesof each bundle being spaced relatively closely to provide restrictedpassages for the efficient heat exchange between liquid flowing in saidpassages and coolant passing through said tubes; and spacing meansproviding, between said baille means and at least one row of tubesadjacent thereto, and between said heated areas of the shell and tubesadjacent thereto, a lbranching system of peripheral and core penetratingfree flow passages of less resistance to the flow of liquid that hasbecome so coldand viscous as to adhere to the tubes, than theresistances of said restricted passages under said conditions, saidperipheral free flow passages being serially connected by said portmeans to provide a substantially continuous free flow channel extending`from said inlet means to said outlet means in substantiallyuninterrupted contact with said heatedv areas of the shell.

8. A cooler for -liquids that are viscous when cold, comprising: ashell; means cooperating with the outer surface f said shell to define awarm up chamber from which heat may be imparted to the shell; baillemeans dividing the space within said shell into a series of flowchamberseach having at least one extremity in contact with the inner surface ofsaid shell in an area covered by said warm up chamber; liquid inlet andoutlet means communicating with said chambers, said baille means andshell cooperating to dei'ine port means through which the liquid mayflow from one of said now chambers to another in uninterrupted contactwith the inner surface of the shell; a bundle of parallel open endedtubes within each of said chambers, arranged in rows generally parallelto said baffle plate, the majority of said tubes of each bundle beingrelatively kclosely spaced for eillcient heat exchange between liquidflowing between said tubes and cooling fluid passing through said tubes:means for spacing each baille plate from an adjacent row of tubes asufllcient distance to provide a passage of less resistance to flow ofthe liquid under congealment conditions in which the liquid tends tocongeal upon the tube surfaces, than the resistance of the passagesbetween the tubes; means providing in each of said chambers a corepenetrating free now passage between adjacent rows of tubes of greaterspacing and less resistance thanl the aforesaid relatively close spacingof the majority of tubes to facilitate penetration of the liquid intosaid bundles when the liquid is viscous; and means for spacing tubesadjacent said shell a distance from said shell sulcient toprovidepassages adjacent the inner surface of the shell, of less resistancethan the majority ofA passages between the tubes, connecting the inletmeans and outlet means respectively to said passages l2 adjacent thebaille plates, and said free flow passages. l 9. A cooler for liquidsthat are viscous when cold, comprising: a shell; means defining a warmup chambery exteriorly of the shell; baille means dividing the interiorof the shell into a tortuous :dow passage one side of which is incontact with the inner surface of the shell in an area covered by saidwarm up chamber, said flow passage having an inlet and an outlet; a,bundle of openended tubes within each portion of thefiow passagedisposed between the baffles, said tubes being in rows generallyparallel to said baiiles and the majority of said'tubes of each bundlebeing relatively closely spaced; means for spacing-the tubes adjacentsaid shell a distance from the inner surface of the heated area of saidshell sufiicient to provide a continuous passage, adjacent said innersurface, of less resistance than the passages between said tubes; andmeans for spacing each baule plate from an adjacent row of tubes asuiilcient distance to provide a passage of less resistance to the ilowof liquid than the above mentioned spacing of the tubes, said passagebeing connected to the above mentioned passage of less resistance.

10. The invention defined by claim 9 wherein there is means forproviding, in each of the portions of the flow path between the bailles,a core penetrating free flow passage between adjacent rows of tubes ofgreater spacing and less ilow resistance than the aforesaid relativelyclose spacing of the majority of tubes, said free flow passage havingone side in communication with said continuous passage. i

11. A cooler for liquids that are viscous when cold, comprising: ashell; means cooperating with the outer surface of said shell to definea warm up chamber from which heat may be imparted to the shell;baillemeans dividing the space within the shell into a series of flowchambers, each having at least one extremity in contact with a heatedarea of the inner surface of the shell; liquid inlet and outlet meansconnected to respective chambers, said baille means being providedwithvports connecting said chambers in series between said inlet andoutlet means to deilne a tortuous how path through the cooler; a corecomprising a bundle of parallel open ended tubes within each of saidchambers, arranged in rows generally parallel to said baille means, themajority of said tubes of each bundle being relatively closely spaced toprovide relatively restricted passages for efficient heat exchangebetween liquid flowing in said passages and coolant passing through saidtubes; means dening between each baille plate and an adjacent row oftubes, a continuous core penetrating free flow passage of lessresistance than said restricted passages under congealment conditions inwhich the liquid tends to congeal upon the tubes; vand means definingbetween the aforesaid heated areas of said shell and the adjacent tubes,peripheral free flow passages connecting the said core penetrating freeflow passages to said inlet Vand outlet means respectively, certain ofsaid ports in said bafile means being positioned in said peripheral freeflow passages to ypermit liquid flowing through said peripheral freeflow passages to pass from one flow chamber to another. 12. A cooler for-liquids that are viscous when cold, comprising: a shell; meanscooperating with the outer surface of said shell to define a warm upchamber from which heat may be imparted to the shell; baille meansdividing the to respective chambers, said baille means being 5 providedwith ports connecting said chambers in series between said inlet andoutlet means to dene a tortuous ow path through the cooler; a corecomprising a bundle of parallel open ended tubes within each of saidchambers, arranged ,10

in rows generally parallel to said baille means, the majority of saidtubesof each'bundle being relatively closely spaced to providerelatively restricted passages for eilicient heat exchange between theliquid ilowing in said passages and 15 coolant passing through saidtubes; means dening between the aforesaid heated area `of said shell andadjacent tubes, peripheral free-ilow passages, said peripheral free-flowpassages being connected to said liquid inlet and liquid outlet 20means. and the portions of said peripheral freeilow passages in said dowchambers being connected to each other through said port means thusforming a tortuous peripheral tree-now passage from said liquid inlet tosaid liquid outlet means; and continuous core penetrating freefiowpassage means extending laterally into said core from said peripheralfree-flow passages whereby oil vin said peripheral free-flow passagesmay iiow inwardly from theside of said core into the central portion ofsaid core.

' SOREN K. ANDERSEN.

REFERENCES CITED The following references are of record in the file ofthis patent: v

' UNITED STATES PATENTS Number Name Date 1,864,052 Dykeman et al. June21, 1932 1,923,404 White et al Aug. 22, 1933 2,071,106 Blair Feb. 16,1937 2,270,864 Blais Jan. 27, 1942 2,307,300 Ramsaur Jan. 5, 19432,354,362 vBurns July 25, 1944 2,359,448 Shaw Oct. 3, 1944 2,359,533Shogran Oct. 3, 1944 `2.373.157 Worth Apr. 10, 1945

